Kinin receptors are expressed in human astrocytic tumour cells

Kinin Receptors and Kinin-Related Gene Expression in Astrocytic Brain Tumors

Kinins are a set of peptides present in tissues that are involved in the inflammatory response and cancer progression. However, studies showing the expression of kinin receptors in human glioma samples are still incomplete and contradictory. The aim of the present study was to ascertain the expression of BDKRB1 and BDKRB2 genes, as well as the level of B1R and B2R proteins in human gliomas, depending on the degree of malignancy. Additionally, representative kinin-dependent genes with altered expression were indicated. The expression profile of kinin-dependent genes was determined using oligonucleotide microarray technique. In addition, RT-qPCR was used to assess the expression level of selected differentiating genes. The location of kinin receptors in brain gliomas was assessed using immunohistochemical methods. The oligonucleotide microarray method was used to identify 12 mRNA IDs of kinin-related genes whose expression was upregulated or downregulated in gliomas of different grades. In immunohistochemically stained samples, the concentrations of BR1 and BR2 proteins, measured by optical density, were statistically significantly higher in grade G3 vs. G2 and G4 vs. G3. Increased expression of kinin receptors BDKRB1 and BDKRB2 in brain gliomas, depending on the degree of malignancy, suggests the involvement of kinins and their receptors in the disease's pathogenesis. Quantitative assessment of mRNA BDKRB1, PRKAR1A, MAP2K, and EGFR in patients with brain tumors may hold diagnostic and therapeutic significance.

Adult brain tumors in Sub-Saharan Africa: A scoping review

BACKGROUND

Sub-Saharan African (SSA) neuro-oncologists report high workloads and challenges in delivering evidence-based care; however, these reports contrast with modeled estimates of adult neuro-oncology disease burden in the region. This scoping review aimed to better understand the reasons for this discrepancy by mapping out the SSA adult brain tumor landscape based on published literature.

METHODS

Systematic searches were conducted in OVID Medline, Global Index Medicus, African Journals Online, Google Scholar, and faculty of medicine libraries from database inception to May 31 st, 2021. The results were summarized quantitatively and narratively. English and French peer-reviewed articles were included (title, abstract, and full text).

RESULTS

Of the 819 records identified, 119 articles by 24 SSA countries (42.9%) were included in the final review. Odeku published the first article in 1967, and nine of the ten most prolific years were in the 21 st century. The greatest contributing region was Western Africa (n=58, 48.7%) led by Nigeria (n=37, 31.1%). Central Africa had fewer articles published later than the other SSA regions (p=0.61). Most studies were non-randomized (n=75, 63.0%) and meningiomas (n=50, 42.0%) were the most common brain tumors reported. Less than 30 studies reported on adjuvant treatment or patient outcomes.

CONCLUSIONS

Most publications were hospital-based, and there was significant heterogeneity in the quality of evidence and reporting. This study highlights the need for rapid and sustainable investments and brain tumor research capacity in SSA.

Neuroendocrine Factors in Melanoma Pathogenesis

Simple Summary

Melanoma is a very aggressive and fatal malignant tumor. While curable if diagnosed in its early stages, advanced melanoma, despite the complex therapeutic approaches, is associated with one of the highest mortality rates. Hence, more and more studies have focused on mechanisms that may contribute to melanoma development and progression. Various studies suggest a role played by neuroendocrine factors which can act directly on tumor cells, modulating their proliferation and metastasis capability, or indirectly through immune or inflammatory processes that impact disease progression. However, there are still multiple areas to explore and numerous unknown features to uncover. A detailed exploration of the mechanisms by which neuroendocrine factors can influence the clinical course of the disease could open up new areas of biomedical research and may lead to the development of new therapeutic approaches in melanoma.

Abstract

Melanoma is one of the most aggressive skin cancers with a sharp rise in incidence in the last decades, especially in young people. Recognized as a significant public health issue, melanoma is studied with increasing interest as new discoveries in molecular signaling and receptor modulation unlock innovative treatment options. Stress exposure is recognized as an important component in the immune-inflammatory interplay that can alter the progression of melanoma by regulating the release of neuroendocrine factors. Various neurotransmitters, such as catecholamines, glutamate, serotonin, or cannabinoids have also been assessed in experimental studies for their involvement in the biology of melanoma. Alpha-MSH and other neurohormones, as well as neuropeptides including substance P, CGRP, enkephalin, beta-endorphin, and even cellular and molecular agents (mast cells and nitric oxide, respectively), have all been implicated as potential factors in the development, growth, invasion, and dissemination of melanoma in a variety of in vitro and in vivo studies. In this review, we provide an overview of current evidence regarding the intricate effects of neuroendocrine factors in melanoma, including data reported in recent clinical trials, exploring the mechanisms involved, signaling pathways, and the recorded range of effects.

Short review of SEC, a potential dexamethasone-sparing regimen for glioblastoma: Spironolactone, ecallantide, clotrimazole

This paper presents a short review of data supporting a dexamethasone sparing regimen, SEC, to reduce glioblastoma related brain edema. The conclusion of the reviewed data is that the rationale and risk/benefit ratio favors a pilot study to determine if the three drug regimen of SEC can reduce need for corticosteroid use during the course of glioblastoma. Details of how selected pathophysiological aspects of brain edema occurring during the course of glioblastoma and its treatment intersect with the established action of the three old drugs of SEC indicate that they can be repurposed to reduce that edema. Current first-line treatment of this edema is dexamethasone or related corticosteroids. There are multiple negative prognostic implications of both the edema itself and of dexamethasone, prime among them shortened survival, making a dexamethasone sparing regimen highly desirable. SEC uses spironolactone, an antihypertensive potassium-sparing diuretic acting by mineralocorticoid receptor inhibition, ecallantide acting to inhibit kallikrein activation marketed to treat hereditary angioedema, and clotrimazole, an old antifungal drug that inhibits intermediate conductance Ca++ activated K+ channel (KCa3.1). These three old drugs are well known to most clinicians, have a well-tolerated safety history, and have a robust preclinical database showing their potential to reduce the specific edema of glioblastoma. Additionally, these three drugs were chosen by virtue of each having preclinical evidence of glioblastoma growth and/or migration inhibition independent of their edema reduction action. A clinical study of SEC is being planned.

Pharmacological Modulation of Blood-Brain Barrier Permeability by Kinin Analogs in Normal and Pathologic Conditions

The blood–brain barrier (BBB) is a major obstacle to the development of effective diagnostics and therapeutics for brain cancers and other central nervous system diseases. Peptide agonist analogs of kinin B1 and B2 receptors, acting as BBB permeabilizers, have been utilized to overcome this barrier. The purpose of the study was to provide new insights for the potential utility of kinin analogs as brain drug delivery adjuvants. In vivo imaging studies were conducted in various animal models (primary/secondary brain cancers, late radiation-induced brain injury) to quantify BBB permeability in response to kinin agonist administrations. Results showed that kinin B1 (B1R) and B2 receptors (B2R) agonists increase the BBB penetration of chemotherapeutic doxorubicin to glioma sites, with additive effects when applied in combination. B2R agonist also enabled extravasation of high-molecular-weight fluorescent dextrans (155 kDa and 2 MDa) in brains of normal mice. Moreover, a systemic single dose of B2R agonist did not increase the incidence of metastatic brain tumors originating from circulating breast cancer cells. Lastly, B2R agonist promoted the selective delivery of co-injected diagnostic MRI agent Magnevist in irradiated brain areas, depicting increased vascular B2R expression. Altogether, our findings suggest additional evidence for using kinin analogs to facilitate specific access of drugs to the brain.

The Role of C1-Esterase Inhibitors in the Management of Vasogenic Edema in Glioblastoma

Glioblastoma (GB) is one of the most common adult primary brain tumors, classified as a grade IV astrocytoma and highly malignant in nature. As the tumor grows and disrupts the blood-brain barrier (BBB), vasogenic edema can result. The edema has the potential to significantly contribute to a patient's morbidity and mortality. Bradykinin has been theorized to play a role in this process as well as encourage tumor spread. Here we discuss a case in which a patient with vasogenic edema and angioedema refractory to antihistamines and high dose corticosteroids responded to C1-esterase inhibitor (C1INH) therapy. Though data exist concerning the role of bradykinin in GB, no clinical studies using C1INH have been done in humans with GB.

Kinins in Glioblastoma Microenvironment

Tumour progression involves interactions among various cancer cell clones, including the cancer stem cell subpopulation and exogenous cellular components, termed cancer stromal cells. The latter include a plethora of tumour infiltrating immunocompetent cells, among which are also immuno-modulatory mesenchymal stem cells, which by vigorous migration to growing tumours and susequent transdifferentiation into various types of tumour-residing stromal cells, may either inhibit or support tumour progression. In the light of the scarce therapeutic options existing for the most malignant brain tumour glioblastoma, mesenchymal stem cells may represent a promising novel tool for cell therapy, e.g. drug delivery vectors. Here, we review the increasing number of reports on mutual interactions between mesenchymal stem cells and glioblastoma cells in their microenvironment. We particularly point out two novel aspects: the different responses of cancer cells to their microenvironmental cues, and to the signalling by kinin receptors that complement the immuno-modulating cytokine-signalling networks. Inflammatory glioblastoma microenvironment is characterised by increasing expression of kinin receptors during progressive glioma malignancy, thus making kinin signalling and kinins themselves rather important in this context. In general, their role in tumour microenvironment has not been explored so far. In addition, kinins also regulate blood brain barrier-related drug transfer as well as brain tumour angiogenesis. These studies support the on-going research on kinin antagonists as candidates in the development of anti-invasive agents for adjuvant glioblastoma therapy.

Noscapine, a Non-addictive Opioid and Microtubule-Inhibitor in Potential Treatment of Glioblastoma

Noscapine is a phthalide isoquinoline alkaloid that easily traverses the blood brain barrier and has been used for years as an antitussive agent with high safety. Despite binding opioid receptors, noscapine lacks significant hypnotic and euphoric effects rendering it safe in terms of addictive potential. In 1954, Hans Lettré first described noscapine as a mitotic poison. The drug was later tested for cancer treatment in the early 1960's, yet no effect was observed likely as a result of its short biological half-life and limited water solubility. Since 1998, it has regained interest thanks to studies from Emory University, which showed its anticancer activity in animal models with negligible toxicity. In contrast to other microtubule-inhibitors, noscapine does not affect the total intracellular tubulin polymer mass. Instead, it forces the microtubules to spend an increased amount of time in a paused state leading to arrest in mitosis and subsequently inducing mitotic slippage/mitotic catastrophe/apoptosis. In experimental models, noscapine does not induce peripheral neuropathy, which is common with other microtubule inhibitors. Noscapine also inhibits tumor growth and enhances cancer chemosensitivity via selective blockage of NF-κB, an important transcription factor in glioblastoma pathogenesis. Due to their anticancer activities and high penetration through the blood-brain barrier, noscapine analogues strongly deserve further study in various animal models of glioblastoma as potential candidates for future patient therapy.

Exploiting cancer's phenotypic guise against itself: targeting ectopically expressed peptide G-protein coupled receptors for lung cancer therapy

Lung cancer, claiming millions of lives annually, has the highest mortality rate worldwide. This advocates the development of novel cancer therapies that are highly toxic for cancer cells but negligibly toxic for healthy cells. One of the effective treatments is targeting overexpressed surface receptors of cancer cells with receptor-specific drugs. The receptors-in-focus in the current review are the G-protein coupled receptors (GPCRs), which are often overexpressed in various types of tumors. The peptide subfamily of GPCRs is the pivot of the current article owing to the high affinity and specificity to and of their cognate peptide ligands, and the proven efficacy of peptide-based therapeutics. The article summarizes various ectopically expressed peptide GPCRs in lung cancer, namely, Cholecystokinin-B/Gastrin receptor, the Bombesin receptor family, Bradykinin B1 and B2 receptors, Arginine vasopressin receptors 1a, 1b and 2, and the Somatostatin receptor type 2. The autocrine growth and pro-proliferative pathways they mediate, and the distinct tumor-inhibitory effects of somatostatin receptors are then discussed. The next section covers how these pathways may be influenced or 'corrected' through therapeutics (involving agonists and antagonists) targeting the overexpressed peptide GPCRs. The review proceeds on to Nano-scaled delivery platforms, which enclose chemotherapeutic agents and are decorated with peptide ligands on their external surface, as an effective means of targeting cancer cells. We conclude that targeting these overexpressed peptide GPCRs is potentially evolving as a highly promising form of lung cancer therapy.

Synthesis and evaluation of a 68Ga-labeled bradykinin B1 receptor agonist for imaging with positron emission tomography

A novel ⁶⁸Ga-labeled bradykinin B1 receptor (B1R) agonist, ⁶⁸Ga-Z01115, was synthesized and evaluated for imaging with positron emission tomography (PET). Z01115 exhibited good binding affinity (K_i=25.4±5.1nM) to hB1R. ⁶⁸Ga-Z01115 was prepared in 74±5 decay-corrected radiochemical yield with >99% radiochemical purity and 155±89GBq/µmol (4.2±2.4Ci/μmol) specific activity. ⁶⁸Ga-Z01115 was stable in vitro in mouse plasma (93% remaining intact after 60min incubation), and relatively stable in vivo (51±5% remaining intact at 5min post-injection). PET imaging and biodistribution studies in mice showed that ⁶⁸Ga-Z01115 cleared rapidly from nontarget tissues/organs, and generated high target-to-nontarget contrast images. The uptake of ⁶⁸Ga-Z01115 in B1R-positive (B1R+) tumor was 5.65±0.59%ID/g at 1h post-injection. Average contrast ratios of B1R+ tumor-to-B1R- tumor, -to-blood and -to-muscle were 24.3, 24.4 and 82.9, respectively. Uptake of ⁶⁸Ga-Z01115 in B1R+ tumors was reduced by ∼90% with co-injection of cold standard, confirming it was mediated by B1R. Our data suggest that ⁶⁸Ga-Z01115 is a promising tracer for imaging the expression of B1R that is overexpressed in a variety of cancers.

ATP/pH Dual Responsive Nanoparticle with d-[des-Arg10 ]Kallidin Mediated Efficient In Vivo Targeting Drug Delivery

Inflammation has been reported as one significant hallmark of breast cancer in relation to tumor development, metastasis, and invasion. The bradykinin receptor 1 (B1R) is highly expressed on inflammatory breast tumor cells thus providing a promising targeting site for tumor recognition and sufficient receptor mediated endocytosis. In this study, the authors evaluate the targeting efficiency of l-form and d-form [des-Arg¹⁰ ]kallidin both in vitro and in vivo. To further improve the drug delivery efficiency, the authors establish a dandelion like nanoparticle by combining the polymeric drug conjugates and aptamer complex together. The doxorubicin conjugated polymer is complexed with adenosine-5'-triphosphate (ATP) sensitive hybridized aptamer in self-assembly process by intercalating into the double strand scaffolds. The acid labile conjugating bond and ATP sensitive aptamer endow the nanoparticle with dual responsiveness to intracellular milieu, thus triggering a quick drug release in tumor cells. Remarkable therapeutic effects and tuned in vivo pharmacokinetics profiles are shown by the aptamer complexed drug conjugates nanoparticle with B1R active targeting modification. Therefore the strategies of B1R targeting and ATP/pH dual-responsiveness nanoparticle help achieve enhanced drug accumulation within tumor cells and efficient chemotherapy for breast cancer.

The role of kinin receptors in cancer and therapeutic opportunities

Kinins are generated within inflammatory tissue microenvironments, where they exert diverse functions, including cell proliferation, leukocyte activation, cell migration, endothelial cell activation and nociception. These pleiotropic functions depend on signaling through two cross talking receptors, the constitutively expressed kinin receptor 2 (B2R) and the inducible kinin receptor 1 (B1R). We have reviewed evidence, which supports the concept that kinin receptors, especially kinin receptor 1, are promising targets for cancer therapy, since (1) many tumor cells express aberrantly high levels of these receptors; (2) some cancers produce kinins and use them as autocrine factors to stimulate their growth; (3) activation of kinin receptors leads to activation of macrophages, dendritic cells and other cells from the tumor microenvironment; (4) kinins have pro-angiogenic properties; (5) kinin receptors have been implicated in cancer migration, invasion and metastasis; and (6) selective antagonists for either B1R or B2R have shown anti-proliferative, anti-inflammatory, anti-angiogenic and anti-migratory properties. The multiple cross talks between kinin receptors and renin-angiotensin system (RAS) as well as its implications for targeting KKS or RAS for the treatment of malignancies are also discussed. It is expected that B1R antagonists would interfere less with housekeeping functions and therefore would be attractive compounds to treat selected types of cancer. Reliable clinical studies are needed to establish the translatability of these data to human settings and the usefulness of kinin receptor antagonists.

Functional and molecular characterization of kinin B1 and B 2 receptors in human bladder cancer: implication of the PI3Kγ pathway

Kinins and their receptors have been recently implicated in cancer. Using functional and molecular approaches, we investigated the relevance of kinin B1 and B2 receptors in bladder cancer. Functional studies were conducted using bladder cancer cell lines, and human biopsies were employed for molecular studies. Both B1 des-Arg(9)-BK and B2 BK receptor agonists stimulated the proliferation of grade 3-derived T24 bladder cancer cells. Furthermore, treatment with B1 and B2 receptor antagonists (SSR240612 and HOE140) markedly inhibited the proliferation of T24 cells. Only higher concentrations of BK increased the proliferation of the grade 1 bladder cancer cell line RT4, while des-Arg(9)-BK completely failed to induce its proliferation. Real-time PCR revealed that the mRNA expression of kinin receptors, particularly B1 receptors, was increased in T24 cells relative to RT4 cells. Data from bladder cancer human biopsies revealed that B1 receptor expression was increased in all tumor samples and under conditions of chronic inflammation. We also show novel evidence demonstrating that the pharmacological inhibition of PI3Kγ (phosphatidylinositol 3-kinase) with AS252424, concentration-dependently reduced T24 cell proliferation induced by BK or des-Arg(9)-BK. Finally, the incubation of T24 cells with kinin agonists led to a marked activation of the PI3K/AKT and ERK 1/2 signaling pathways, whereas p38 MAP kinase remained unaffected. Kinin receptors, especially B1 receptors, appear to be implicated in bladder cancer progression. It is tempting to suggest that selective kinin antagonists might represent potential alternative therapies for bladder cancer.

Induction of selective blood-tumor barrier permeability and macromolecular transport by a biostable kinin B1 receptor agonist in a glioma rat model

Treatment of malignant glioma with chemotherapy is limited mostly because of delivery impediment related to the blood-brain tumor barrier (BTB). B1 receptors (B1R), inducible prototypical G-protein coupled receptors (GPCR) can regulate permeability of vessels including possibly that of brain tumors. Here, we determine the extent of BTB permeability induced by the natural and synthetic peptide B1R agonists, LysdesArg⁹BK (LDBK) and SarLys[dPhe⁸]desArg⁹BK (NG29), in syngeneic F98 glioma-implanted Fischer rats. Ten days after tumor inoculation, we detected the presence of B1R on tumor cells and associated vasculature. NG29 infusion increased brain distribution volume and uptake profiles of paramagnetic probes (Magnevist and Gadomer) at tumoral sites (T₁-weighted imaging). These effects were blocked by B1R antagonist and non-selective cyclooxygenase inhibitors, but not by B2R antagonist and non-selective nitric oxide synthase inhibitors. Consistent with MRI data, systemic co-administration of NG29 improved brain tumor delivery of Carboplatin chemotherapy (ICP-Mass spectrometry). We also detected elevated B1R expression in clinical samples of high-grade glioma. Our results documented a novel GPCR-signaling mechanism for promoting transient BTB disruption, involving activation of B1R and ensuing production of COX metabolites. They also underlined the potential value of synthetic biostable B1R agonists as selective BTB modulators for local delivery of different sized-therapeutics at (peri)tumoral sites.

Glial cells in (patho)physiology

Neuroglial cells define brain homeostasis and mount defense against pathological insults. Astroglia regulate neurogenesis and development of brain circuits. In the adult brain, astrocytes enter into intimate dynamic relationship with neurons, especially at synaptic sites where they functionally form the tripartite synapse. At these sites, astrocytes regulate ion and neurotransmitter homeostasis, metabolically support neurons and monitor synaptic activity; one of the readouts of the latter manifests in astrocytic intracellular Ca(2+) signals. This form of astrocytic excitability can lead to release of chemical transmitters via Ca(2+) -dependent exocytosis. Once in the extracellular space, gliotransmitters can modulate synaptic plasticity and cause changes in behavior. Besides these physiological tasks, astrocytes are fundamental for progression and outcome of neurological diseases. In Alzheimer's disease, for example, astrocytes may contribute to the etiology of this disorder. Highly lethal glial-derived tumors use signaling trickery to coerce normal brain cells to assist tumor invasiveness. This review not only sheds new light on the brain operation in health and disease, but also points to many unknowns.

Bradykinin promotes the chemotactic invasion of primary brain tumors

Primary brain tumors, gliomas, diffusely invade the brain by active cell migration either intraparenchymal, along white matter tracts or along blood vessels. The close relationship of glioma with the vasculature assures a continuous supply of oxygen and nutrients essential for cell growth, and exposes cells to a variety growth factors, chemokines, cytokines, and kinins. Signals that attract glioma cells to blood vessels are poorly understood. It has been shown that vascular endothelial cells can initiate the bradykinin (BK) signaling cascade and two bradykinin receptors, B1 and B2, have been identified and cloned. In this study we show that glioma cells isolated from patient biopsies express bradykinin 2 receptors (B2R) whose activation causes intracellular Ca(2+) oscillations. Through time-lapse video-microscopy experiments we show that BK significantly enhances glioma cell migration/invasion. We further show that BK acts as a chemoattractant guiding glioma cells toward blood vessels in acute rat brain slices. The number of cells associated with blood vessels is decreased when B2R are either pharmacologically inhibited or B2R eliminated through short-hairpin RNA knockdown. These data strongly suggest that bradykinin, acting via B2R, acts as an important signal directing the invasion of glioma cells toward blood vessels. A clinically approved B2R antagonist is available that could be used as anti-invasive drug in glioma patients in the future.

Bradykinin increases resensitization of purinergic receptor signaling in glioma cells

BACKGROUND

Purinergic receptor-mediated signaling plays an important role in the function of glial cells, including glial tumor cells. Bradykinin is also an important paracrine mediator which is highly expressed in brain tumors and may correlate with their pathological grade. Interaction between bradykinin and purinergic signaling may therefore be involved in the regulation of glial tumor cells.

RESULTS

We examined the effect of bradykinin on glial purinergic signaling in an immortalized glioma cell line. Confocal calcium imaging revealed that ATP evokes an increase in [Ca2+]i in the U87 human astrocytoma cell line. This response was reduced with repetitive application of ATP, likely due to receptor desensitization. However exposure to bradykinin increased the Ca2+ response to a second application of ATP, consistent with increased resensitization. The bradykinin effect on resensitization was similar in the absence of extracellular Ca2+ or in the presence of the PKC activator PMA, but was inhibited by the protein phosphatase inhibitor okadaic acid and the PI3K inhibitor LY294002.

CONCLUSIONS

Modulation of protein phosphatases and the PI3K pathway may represent a mechanism by which bradykinin potentiates purinergic signaling in glial cells.

Selective tumor blood-brain barrier opening with the kinin B2 receptor agonist [Phe(8)psi(CH(2)NH)Arg(9)]-BK in a F98 glioma rat model: an MRI study

Treatment of malignant glioma with chemotherapy is limited mostly because of delivery impediment related to the blood-brain barrier (BBB). One approach for transporting drugs across the BBB involves the activation of bradykinin-B2 receptors (BK-B2R). Our objective was to pharmacologically characterize the BBB permeability induced by the synthetic biostable BK-B2R analogue [Phe(8)psi(CH(2)NH)Arg(9)]-BK (R523) in F98 glioma-implanted Fischer rats. On day 10 post-inoculation, we detected the presence of B2R in the tumor cells and the peritumoral microvasculature (RT-PCR and immunohistochemistry). We assessed BBB permeability before and after the intracarotid (i.c.) infusion of R523 (0.1ml/min for 5min; 2.5, 10, and 50nmol/kg/min) using non-invasive dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) with the different sized-contrast agents Gd-DTPA (0.5kDa) and Gadomer (17kDa) (0.25mmol/kg via the caudal vein). T(1)-weighted images were analyzed for the presence or absence of contrast enhancement within and surrounding the tumor area and mathematically processed to yield a contrast agent distribution volume (CADV), which was used as an indicator of vascular permeability. Our results showed that the agonist R523 increased, in a dose-dependent manner, the CADV indexes of Gd-DTPA and Gadomer, with a maximum 2-fold increase in brain uptake of both CA. The increase in CADV induced by R523 (10nmol/kg/min) was prevented by the B2R antagonist HOE140 (20nmol/kg/min, i.c.) and the nitric oxide synthase inhibitor L-NA (5mg/kg, i.v.) but not by the B1R antagonist R892 (20nmol/kg/min, i.c.) or the cyclooxygenase inhibitor Meclofenamate (5mg/kg, i.v.). The BBB permeabilizing effect of R523 (10nmol/kg/min) lasted for <1h and was accompanied by a dose-related fall in arterial blood pressure. We concluded that R523 allows the extravasation of hydrophilic macromolecular agents (17kDa) into tumor tissues by inducing selective tumor BBB permeability via B2R- and NO-dependent mechanisms.

Bradykinin increases the secretion and expression of endothelin-1 through kinin B2 receptors in melanoma cells

The present study was conducted to determine whether bradykinin would affect the secretion and expression of endothelin-1 (ET-1) in B16-BL6 melanoma cells. Bradykinin administered to cultured melanoma cells increased preproET-1 mRNA level and the secretion of ET-1. Although kinin B(1) and B(2) receptor mRNAs are expressed in the melanoma cells, the increase of preproET-1 mRNA expression and the secretion of ET-1 were inhibited by kinin B(2), but not by B(1), receptor antagonist. These results suggest that bradykinin regulates the secretion and biosynthesis of ET-1 through kinin B(2) receptor in tumor cells, especially melanoma cells.

Metabolically stable bradykinin B2 receptor agonists enhance transvascular drug delivery into malignant brain tumors by increasing drug half-life

BACKGROUND

The intravenous co-infusion of labradimil, a metabolically stable bradykinin B2 receptor agonist, has been shown to temporarily enhance the transvascular delivery of small chemotherapy drugs, such as carboplatin, across the blood-brain tumor barrier. It has been thought that the primary mechanism by which labradimil does so is by acting selectively on tumor microvasculature to increase the local transvascular flow rate across the blood-brain tumor barrier. This mechanism of action does not explain why, in the clinical setting, carboplatin dosing based on patient renal function over-estimates the carboplatin dose required for target carboplatin exposure. In this study we investigated the systemic actions of labradimil, as well as other bradykinin B2 receptor agonists with a range of metabolic stabilities, in context of the local actions of the respective B2 receptor agonists on the blood-brain tumor barrier of rodent malignant gliomas.

METHODS

Using dynamic contrast-enhanced MRI, the pharmacokinetics of gadolinium-diethyltriaminepentaacetic acid (Gd-DTPA), a small MRI contrast agent, were imaged in rodents bearing orthotopic RG-2 malignant gliomas. Baseline blood and brain tumor tissue pharmacokinetics were imaged with the 1st bolus of Gd-DTPA over the first hour, and then re-imaged with a 2nd bolus of Gd-DTPA over the second hour, during which normal saline or a bradykinin B2 receptor agonist was infused intravenously for 15 minutes. Changes in mean arterial blood pressure were recorded. Imaging data was analyzed using both qualitative and quantitative methods.

RESULTS

The decrease in systemic blood pressure correlated with the known metabolic stability of the bradykinin B2 receptor agonist infused. Metabolically stable bradykinin B2 agonists, methionine-lysine-bradykinin and labradimil, had differential effects on the transvascular flow rate of Gd-DTPA across the blood-brain tumor barrier. Both methionine-lysine-bradykinin and labradimil increased the blood half-life of Gd-DTPA sufficiently enough to increase significantly the tumor tissue Gd-DTPA area under the time-concentration curve.

CONCLUSION

Metabolically stable bradykinin B2 receptor agonists, methionine-lysine-bradykinin and labradimil, enhance the transvascular delivery of small chemotherapy drugs across the BBTB of malignant gliomas by increasing the blood half-life of the co-infused drug. The selectivity of the increase in drug delivery into the malignant glioma tissue, but not into normal brain tissue or skeletal muscle tissue, is due to the inherent porous nature of the BBTB of malignant glioma microvasculature.

Stimulation of the bradykinin B(1) receptor induces the proliferation of estrogen-sensitive breast cancer cells and activates the ERK1/2 signaling pathway

Kinin peptides exert multiple biological effects by binding to two types of G protein-coupled receptors known as B(1) (B(1)R) and B(2) receptors. Expression of the B(1)R in human breast cancer was recently reported, but up to now the consequences of its stimulation are unknown. Our aims were (1) to investigate the capacity of B(1)R to trigger cell proliferation in breast cancer cells, (2) to explore some of the downstream events occurring after B(1)R stimulation that may be linked to cell proliferation, and (3) to determine whether human breast tumors express potentially active B(1)R assessed by the binding of a radiolabeled agonist. Breast cancer cells expressed both the mRNA and the immunoreactive protein of B(1)R that once stimulated triggered cell proliferation at nanomolar concentrations of the ligand. Inhibitor studies suggested that the proliferative effects depend on the activity of epidermal growth factor receptor and subsequent ERK1/2 mitogen-activated protein kinases phosphorylation. B(1)R binding sites, were detected in 3/4 fibroadenomas, in 4/4 ductal carcinomas in situ and in 11/13 invasive ductal carcinomas. The B(1)R-epidermal growth factor receptor crosstalk may be a key interaction that maintains tumor growth, and antagonism of B(1)R may be a valuable alternative for the treatment of breast cancer.

Expression of tissue and plasma kallikreins and kinin B1 and B2 receptors in lung cancer

Tissue kallikrein (hK1) and plasma kallikrein (PK, hKB1) are serine proteases that produce biologically active kinin peptides from endogenous kininogen substrates. There is evidence linking the kallikreins and the mitogenic kinin peptides to carcinogenesis. The aim of this study was to investigate the expression of tissue prokallikrein (pro-hK1), plasma prekallikrein (PPK, pre-hKB1) and kinin B1 and B2 receptor proteins in different subtypes of lung cancer. Immunohistochemistry, using specific antibodies, was performed on archived normal lung sections and sections from adenocarcinomas, squamous cell carcinomas, large cell carcinomas, small cell carcinomas and carcinoid tumours of the lung. Immunoperoxidase labelling was visualised by brightfield microscopy and immunofluorescence labelling by confocal microscopy. Extensive cytoplasmic expression of pro-hK1 and PPK was observed, which was similar in small cell and non-small cell tumours. However, nuclear labelling for the kallikreins was absent or limited. The kinin B1 and B2 receptors were highly expressed in the cytoplasm of all tumour types and in the nuclei of non-small cell tumours. Further studies are required to assess the functional significance of the expression of hK1, PK and kinin receptors in lung tumours, and whether any of these proteins may be potential biomarkers for specific subtypes of lung carcinoma.

Participation of kallikrein-kinin system in different pathologies

The general description of kinins refers to these peptides as molecules involved in vascular tone regulation and inflammation. Nevertheless, in the last years a series of evidences has shown that local hormonal systems, such as the kallikrein-kinin system, may be differently regulated and are of pivotal importance to pathophysiological control. The combined interpretations of many recent studies allow us to conclude that the kallikrein-kinin system plays broader and richer roles than those classically described until recently. In this review, we report findings concerning the participation of the kallikrein-kinin system in inflammation, cancer, and in pathologies related to cardiovascular, renal and central nervous systems.

Bradykinin-induced blood-brain tumor barrier permeability increase is mediated by adenosine 5'-triphosphate-sensitive potassium channel

Bradykinin has been shown to selectively transiently increase the permeability of the blood-brain barrier (BBB). This study was performed to determine whether ATP-sensitive potassium (K(ATP)) channels mediate the increase in permeability of brain tumor microvessels induced by BK. Using a rat brain glioma (C6) model, we found increased expression of K(ATP) channels at tumor sites via Western blot analysis, after intracarotid infusion of bradykinin at a dose of 10 microg/kg/min for 15 min. A significant increase (73.58%) of the integrated density value (IDV) of the K(ATP) channel Kir6.2 subunit was observed in rats with glioma after 10 min of bradykinin perfusion. The over-expression of K(ATP) channels with bradykinin was significantly attenuated by the K(ATP) channel antagonist glibenclamide. Immunohistochemistry and immunolocalization experiments showed that the over-expression of K(ATP) channels was more obvious near tumor capillaries of 10 microm in diameter. I(KATP) modulation by bradykinin in cultured C6 cells was also studied using the patch-clamp technique in a whole-cell configuration. Administration of bradykinin led to a significant opening of K(ATP) channels in a time-dependent manner. This led to the conclusion that the bradykinin-mediated BBB permeability increase is due to accelerated formation of K(ATP) channels, which are thus as an important target in the biochemical regulation of this process.

Non-peptide antagonists for kinin B1 receptors: new insights into their therapeutic potential for the management of inflammation and pain

Kinin B1 and B2 receptors are central to the aetiology of pain and inflammation. Constitutive B2 receptors are commonly associated with the acute phase of inflammation and nociception, whereas the inducible B1 receptors are mostly linked to the chronic or persistent phase (or both). Therefore, selective, orally active kinin B1 receptor antagonists could be potentially therapeutic. B1 receptor antagonists have long been exclusively peptides, but recently a few non-peptide representatives have been identified. The clinical potential of these non-peptide molecules has not yet been evaluated, but they might have a role in treating persistent inflammation and pain, especially when no satisfactory therapy is available. This review summarizes recent advances in the identification and the potential therapeutic properties of these molecules.

Tissue kallikrein and kinin receptor expression in an angiogenic co-culture neuroblastoma model

The sprouting of new blood vessels from pre-existing vasculature (angiogenesis) is essential for tumour survival, influenced by tumour cell-endothelial cell interactions and is tightly regulated by biochemical cues including the kallikrein-kinin system (KKS). We examined the structural interaction between neuroblastomas and endothelial cells (HUVECs) in 2-D and 3-D (matrigel) in vitro, co-culture models by light microscopy, and performed in situ mono- and co-labelling of various KKS proteins. Neuroblastomas formed footplate-like multiple contacts on angiogenic HUVECs without disrupting differentiation of HUVECs into cord-like structures. Tissue kallikrein and the kinin B1R and B2R receptors were demonstrated on interacting neuroblastomas and HUVECs to varying degrees, as well as at actual heterogeneous contact zones in both 2-D and 3-D models. This KKS immuno-reactivity was generally confined to peri-nuclear regions on HUVECs but concentrated on cell extensions on neuroblastomas. The KKS, known to enhance DNA synthesis and process pro-angiogenic precursors of both tumour cells and the extra-cellular matrix, may, by its multi-functional activities at sites of tumour-blood vessel interactions, regulate aspects of both angiogenesis and tumourigenesis.

Identification of oligodendroglioma specific chromosomal copy number changes in the glioblastoma MI-4 cell line by array-CGH and FISH analyses

Glioblastomas, the most frequent and malignant glial tumors, are known to be phenotypically heterogeneous. A low fraction of glioblastomas is associated with specific chromosomal losses at 1p and 19q, which are commonly found in oligodendrogliomas and are generally considered to be a primary event in the development of these tumors. Subsequent progression of oligodendroglial tumors appears to be triggered by additional molecular features underlying the transition to anaplastic oligodendroglioma and glioblastoma multiforme (GBM) such as deletions of 9p and 10q, and alterations of CDKN2A (p16), which is located at 9p21. These findings strengthen the view that GBM on rare occasions may develop from oligodendroglial differentiated cells. In the present study, we evaluated the newly established MI-4 glioblastoma cell line, which displays 1p and 19q specific alterations targeting preferential regions of allelic loss in glial neoplasms, by array-CGH and fluorescence in situ hybridization (FISH) analyses that were combined to obtain a high resolution map of targeted chromosome rearrangements and copy number changes throughout the genome. Genome-wide and chromosome 19 full coverage array-CGH analysis of the MI-4 cell line revealed that in this particular cell line, 1p-specific loss, including the CDKN2 (p18) gene, is not accompanied by loss of the previously described 19q13.3 tumor suppressor candidate region. Interestingly, the array-CGH (CGHa) profile showed an increase in copy number along most of 19q including the AKT2 oncogene and the KLKs gene family, which have previously been shown to be amplified in pancreatic carcinomas and upregulated in several tumors, respectively. The concomitant 1p partial loss and chromosome 19 alterations, with the +7 and -10-specific GBM markers associated with homozygous deletion of 9p21.3 including CDKN2A (p16), are distinct features of the glioblastoma MI-4 cell line, illustrating its origin from an olidodendroglial tumor. Based on these results, we conclude that the MI-4 glioblastoma cell line might function as a model system for investigations into the behavior of a defined oligodendroglioma subtype.

International union of pharmacology. XLV. Classification of the kinin receptor family: from molecular mechanisms to pathophysiological consequences

Kinins are proinflammatory peptides that mediate numerous vascular and pain responses to tissue injury. Two pharmacologically distinct kinin receptor subtypes have been identified and characterized for these peptides, which are named B1 and B2 and belong to the rhodopsin family of G protein-coupled receptors. The B2 receptor mediates the action of bradykinin (BK) and lysyl-bradykinin (Lys-BK), the first set of bioactive kinins formed in response to injury from kininogen precursors through the actions of plasma and tissue kallikreins, whereas the B(1) receptor mediates the action of des-Arg9-BK and Lys-des-Arg9-BK, the second set of bioactive kinins formed through the actions of carboxypeptidases on BK and Lys-BK, respectively. The B2 receptor is ubiquitous and constitutively expressed, whereas the B1 receptor is expressed at a very low level in healthy tissues but induced following injury by various proinflammatory cytokines such as interleukin-1beta. Both receptors act through G alpha(q) to stimulate phospholipase C beta followed by phosphoinositide hydrolysis and intracellular free Ca2+ mobilization and through G alpha(i) to inhibit adenylate cyclase and stimulate the mitogen-activated protein kinase pathways. The use of mice lacking each receptor gene and various specific peptidic and nonpeptidic antagonists have implicated both B1 and B2 receptors as potential therapeutic targets in several pathophysiological events related to inflammation such as pain, sepsis, allergic asthma, rhinitis, and edema, as well as diabetes and cancer. This review is a comprehensive presentation of our current understanding of these receptors in terms of molecular and cell biology, physiology, pharmacology, and involvement in human disease and drug development.

Kinin B1 receptors: key G-protein-coupled receptors and their role in inflammatory and painful processes

Kinins are a family of peptides implicated in several pathophysiological events. Most of their effects are likely mediated by the activation of two G-protein-coupled receptors: B(1) and B(2). Whereas B(2) receptors are constitutive entities, B(1) receptors behave as key inducible molecules that may be upregulated under some special circumstances. In this context, several recent reports have investigated the importance of B(1) receptor activation in certain disease models. Furthermore, research on B(1) receptors in the last years has been mainly focused in determining the mechanisms and pathways involved in the process of induction. This was essentially favoured by the advances obtained in molecular biology studies, as well as in the design of selective and stable peptide and nonpeptide kinin B(1) receptor antagonists. Likewise, development of kinin B(1) receptor knockout mice greatly helped to extend the evidence about the relevance of B(1) receptors during pathological states. In the present review, we attempted to remark the main advances achieved in the last 5 years about the participation of kinin B(1) receptors in painful and inflammatory disorders. We have also aimed to point out some groups of chronic diseases, such as diabetes, arthritis, cancer or neuropathic pain, in which the strategic development of nonpeptidic oral-available and selective B(1) receptor antagonists could have a potential relevant therapeutic interest.

Enhancement of blood-tumor barrier permeability by Sar-[D-Phe8]des-Arg9BK, a metabolically resistant bradykinin B1 agonist, in a rat C6 glioma model

Background

While it is well known that bradykinin B2 agonists increase plasma protein extravasation (PPE) in brain tumors, the bradykinin B1 agonists tested thus far are unable to produce this effect. Here we examine the effect of the selective B1 agonist bradykinin (BK) Sar-[D-Phe8]des-Arg9BK (SAR), a compound resistant to enzymatic degradation with prolonged activity on PPE in the blood circulation in the C6 rat glioma model.

Results

SAR administration significantly enhanced PPE in C6 rat brain glioma compared to saline or BK (p < 0.01). Pre-administration of the bradykinin B1 antagonist [Leu8]-des-Arg (100 nmol/Kg) blocked the SAR-induced PPE in the tumor area.

Conclusions

Our data suggest that the B1 receptor modulates PPE in the blood tumor barrier of C6 glioma. A possible role for the use of SAR in the chemotherapy of gliomas deserves further study.

Host stromal bradykinin B2 receptor signaling facilitates tumor-associated angiogenesis and tumor growth

We evaluated the significance of the host kallikrein-kinin system in tumor angiogenesis and tumor growth using two rodent models genetically deficient in a kallikrein-kinin system. Inoculation of Walker 256 carcinoma cells into the s.c. tissues of the back of normal Brown Norway Kitasato rats (BN-Ki rats) resulted in the rapid development of solid tumors with marked angiogenesis. By contrast, in kininogen-deficient Brown Norway Katholiek rats (BN-Ka rats), which cannot generate intrinsic bradykinin (BK), the weights of the tumors and the extent of angiogenesis were significantly less than those in BN-Ki rats. Daily administration of B(2) receptor antagonists significantly reduced angiogenesis and tumor weights in BN-Ki rats to levels similar to those in BN-Ka rats but did not do so in BN-Ka rats. Angiogenesis and tumor growth were significantly suppressed in B(2) receptor knockout mice bearing sarcoma 180 compared with their wild-type counterparts. Immunoreactive vascular endothelial growth factor (VEGF) was localized in Walker tumor stroma more extensively in BN-Ki rats than in BN-Ka rats, although immunoreactive B(2) receptor also was detected in the stroma to the same extent in both types of rats. Cultured stromal fibroblasts isolated from BN-Ki rats and BN-Ka rats produced VEGF in response to BK (10(-8)-10(-6) m), and this stimulatory effect of BK was abolished with a B(2) receptor antagonist, Hoe140 (10(-5) m). These results suggest that BK generated from kininogens supplied from the host may facilitate tumor-associated angiogenesis and tumor growth by stimulating stromal B(2) signaling to up-regulate VEGF production mainly in fibroblasts.

Tumour metabolites regulate tissue kallikrein in human umbilical vein endothelial cells

Angiogenesis, the sprouting of new blood vessels, is tightly mediated via a myriad of endogenous factors. A pro-angiogenic alteration facilitates the formation of neovascular tumour networks, thereby providing mechanisms for uncontrolled growth. The kallikrein-kinin system is postulated to be pro-angiogenic since its components have been detected in both endothelial cells and tumour tissue. No studies have, however, focussed on the role of tissue kallikrein (TK) in human angiogenic endothelial cell-tumour interactions. This study has optimised a challenge model whereby endothelial cells are presented with neuroblastoma metabolites, and vice versa. Image analysis of immunoreactive TK revealed a dose-dependant, significant reduction of TK localisation within endothelial cells, while gene expression remained unchanged, the latter determined by in situ RT-PCR. Neuroblastoma cells, when challenged with endothelial cell metabolites, displayed no change in TK synthesis or localisation. Alterations in TK synthesis and/or storage by angiogenic endothelial cells may be mediated by tumour-released signals and possibly indicate a shift from a proteolytic to a mitogenic function of TK. The challenge model provides a relatively simple experimental system to study angiogenic factors in tumour-endothelial cell interaction, and is the first to localise both TK and its mRNA within angiogenic endothelial and tumour cells.

Kallikrein cascade and cytokines in inflamed joints

Rheumatoid arthritis is a chronic multi-system disease of unknown aetiology. The current hypothesis is that an unknown antigen triggers an autoimmune response in a genetically susceptible individual. The predominant pathological change is that of an inflammatory synovitis, characterised by cellular infiltrates and angiogenesis, with subsequent bone and cartilage destruction. These pathological changes are as a result of the activation of a variety of cells, inflammatory mediators, and effector molecules. The pro-inflammatory kinins and cytokines appear to play a central role in the pathogenesis of rheumatoid arthritis. Sufficient evidence exists that establishes a key role for the kallikrein-kinin cascade in inflamed joints. In addition, there appears to be an inter-relationship between cytokines and kinins in the inflammatory process. Kinins induce the release of cytokines, and cytokines have been shown to augment the effects of kinins. This may lead to an enhancement and perpetuation of the inflammatory process. In this review, we report a first study, correlating markers of disease with the kallikrein-kinin cascade and with cytokines.

Identification of bradykinin receptors in clinical cancer specimens and murine tumor tissues

Bradykinin (BK) has multiple pathophysiologic functions such as induction of vascular permeability and mitogenesis, and it triggers the release of other mediators such as nitric oxide in inflammatory and cancer tissues. To explore the pathophysiologic roles of BK in tumor, we examined the distribution of BK B2 receptors in human adenocarcinoma (lung, stomach), lymphoma (lymph node), hepatoma, squamous cell carcinoma (lung) and carcinoid (duodenum), and in mouse colon adenocarcinoma 38 (C-38) and sarcoma 180 (S-180) tumor tissues. Immunohistochemical staining of tumor tissues with an anti-BK B2 receptor antibody, or autoradiography with the B2 receptor antagonist [125I]HOE 140 (D-Arg-[Hyp Thi D-Tic Oic8]-BK) and the B2 receptor agonist [3H]BK indicated the presence of B2 receptors in all human tumor cells and murine S-180 and C-38 cells. Specific binding of [3H]HOE 140 was observed in S-180 cells with a Kd of 2.1 nM. Binding of [125I]HOE 140 to S-180 cells was competed by an excess amount (20-100 times) of nonradiolabeled HOE 140 or BK, but not by BK B1 receptor agonist des-Arg9-BK. These results provide direct evidence that the BK B2 receptor is expressed in human cancer and experimental murine tumors, which suggests a potential role for BK in inducing pathologic signal transduction in cancer growth and progression, nitric oxide production and vascular permeability enhancement in tumors. BK antagonists may thus have applications in the modulation of cancer growth and in paraneoplastic syndromes.